linux-stable.git/net/ipv6, branch v4.11.2

tcp: randomize timestamps on syncookies

2017-05-14T12:06:02+00:00

[ Upstream commit 84b114b98452c431299d99c135f751659e517acb ]

Whole point of randomization was to hide server uptime, but an attacker
can simply start a syn flood and TCP generates 'old style' timestamps,
directly revealing server jiffies value.

Also, TSval sent by the server to a particular remote address vary
depending on syncookies being sent or not, potentially triggering PAWS
drops for innocent clients.

Lets implement proper randomization, including for SYNcookies.

Also we do not need to export sysctl_tcp_timestamps, since it is not
used from a module.

In v2, I added Florian feedback and contribution, adding tsoff to
tcp_get_cookie_sock().

v3 removed one unused variable in tcp_v4_connect() as Florian spotted.

Fixes: 95a22caee396c ("tcp: randomize tcp timestamp offsets for each connection")
Signed-off-by: Eric Dumazet 
Reviewed-by: Florian Westphal 
Tested-by: Florian Westphal 
Cc: Yuchung Cheng 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv6: reorder ip6_route_dev_notifier after ipv6_dev_notf

2017-05-14T12:06:02+00:00

[ Upstream commit 242d3a49a2a1a71d8eb9f953db1bcaa9d698ce00 ]

For each netns (except init_net), we initialize its null entry
in 3 places:

1) The template itself, as we use kmemdup()
2) Code around dst_init_metrics() in ip6_route_net_init()
3) ip6_route_dev_notify(), which is supposed to initialize it after
   loopback registers

Unfortunately the last one still happens in a wrong order because
we expect to initialize net->ipv6.ip6_null_entry->rt6i_idev to
net->loopback_dev's idev, thus we have to do that after we add
idev to loopback. However, this notifier has priority == 0 same as
ipv6_dev_notf, and ipv6_dev_notf is registered after
ip6_route_dev_notifier so it is called actually after
ip6_route_dev_notifier. This is similar to commit 2f460933f58e
("ipv6: initialize route null entry in addrconf_init()") which
fixes init_net.

Fix it by picking a smaller priority for ip6_route_dev_notifier.
Also, we have to release the refcnt accordingly when unregistering
loopback_dev because device exit functions are called before subsys
exit functions.

Acked-by: David Ahern 
Tested-by: David Ahern 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv6: initialize route null entry in addrconf_init()

2017-05-14T12:06:02+00:00

[ Upstream commit 2f460933f58eee3393aba64f0f6d14acb08d1724 ]

Andrey reported a crash on init_net.ipv6.ip6_null_entry->rt6i_idev
since it is always NULL.

This is clearly wrong, we have code to initialize it to loopback_dev,
unfortunately the order is still not correct.

loopback_dev is registered very early during boot, we lose a chance
to re-initialize it in notifier. addrconf_init() is called after
ip6_route_init(), which means we have no chance to correct it.

Fix it by moving this initialization explicitly after
ipv6_add_dev(init_net.loopback_dev) in addrconf_init().

Reported-by: Andrey Konovalov 
Signed-off-by: Cong Wang 
Tested-by: Andrey Konovalov 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv4, ipv6: ensure raw socket message is big enough to hold an IP header

2017-05-14T12:06:02+00:00

[ Upstream commit 86f4c90a1c5c1493f07f2d12c1079f5bf01936f2 ]

raw_send_hdrinc() and rawv6_send_hdrinc() expect that the buffer copied
from the userspace contains the IPv4/IPv6 header, so if too few bytes are
copied, parts of the header may remain uninitialized.

This bug has been detected with KMSAN.

For the record, the KMSAN report:

==================================================================
BUG: KMSAN: use of unitialized memory in nf_ct_frag6_gather+0xf5a/0x44a0
inter: 0
CPU: 0 PID: 1036 Comm: probe Not tainted 4.11.0-rc5+ #2455
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x143/0x1b0 lib/dump_stack.c:52
 kmsan_report+0x16b/0x1e0 mm/kmsan/kmsan.c:1078
 __kmsan_warning_32+0x5c/0xa0 mm/kmsan/kmsan_instr.c:510
 nf_ct_frag6_gather+0xf5a/0x44a0 net/ipv6/netfilter/nf_conntrack_reasm.c:577
 ipv6_defrag+0x1d9/0x280 net/ipv6/netfilter/nf_defrag_ipv6_hooks.c:68
 nf_hook_entry_hookfn ./include/linux/netfilter.h:102
 nf_hook_slow+0x13f/0x3c0 net/netfilter/core.c:310
 nf_hook ./include/linux/netfilter.h:212
 NF_HOOK ./include/linux/netfilter.h:255
 rawv6_send_hdrinc net/ipv6/raw.c:673
 rawv6_sendmsg+0x2fcb/0x41a0 net/ipv6/raw.c:919
 inet_sendmsg+0x3f8/0x6d0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:633
 sock_sendmsg net/socket.c:643
 SYSC_sendto+0x6a5/0x7c0 net/socket.c:1696
 SyS_sendto+0xbc/0xe0 net/socket.c:1664
 do_syscall_64+0x72/0xa0 arch/x86/entry/common.c:285
 entry_SYSCALL64_slow_path+0x25/0x25 arch/x86/entry/entry_64.S:246
RIP: 0033:0x436e03
RSP: 002b:00007ffce48baf38 EFLAGS: 00000246 ORIG_RAX: 000000000000002c
RAX: ffffffffffffffda RBX: 00000000004002b0 RCX: 0000000000436e03
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000003
RBP: 00007ffce48baf90 R08: 00007ffce48baf50 R09: 000000000000001c
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000401790 R14: 0000000000401820 R15: 0000000000000000
origin: 00000000d9400053
 save_stack_trace+0x16/0x20 arch/x86/kernel/stacktrace.c:59
 kmsan_save_stack_with_flags mm/kmsan/kmsan.c:362
 kmsan_internal_poison_shadow+0xb1/0x1a0 mm/kmsan/kmsan.c:257
 kmsan_poison_shadow+0x6d/0xc0 mm/kmsan/kmsan.c:270
 slab_alloc_node mm/slub.c:2735
 __kmalloc_node_track_caller+0x1f4/0x390 mm/slub.c:4341
 __kmalloc_reserve net/core/skbuff.c:138
 __alloc_skb+0x2cd/0x740 net/core/skbuff.c:231
 alloc_skb ./include/linux/skbuff.h:933
 alloc_skb_with_frags+0x209/0xbc0 net/core/skbuff.c:4678
 sock_alloc_send_pskb+0x9ff/0xe00 net/core/sock.c:1903
 sock_alloc_send_skb+0xe4/0x100 net/core/sock.c:1920
 rawv6_send_hdrinc net/ipv6/raw.c:638
 rawv6_sendmsg+0x2918/0x41a0 net/ipv6/raw.c:919
 inet_sendmsg+0x3f8/0x6d0 net/ipv4/af_inet.c:762
 sock_sendmsg_nosec net/socket.c:633
 sock_sendmsg net/socket.c:643
 SYSC_sendto+0x6a5/0x7c0 net/socket.c:1696
 SyS_sendto+0xbc/0xe0 net/socket.c:1664
 do_syscall_64+0x72/0xa0 arch/x86/entry/common.c:285
 return_from_SYSCALL_64+0x0/0x6a arch/x86/entry/entry_64.S:246
==================================================================

, triggered by the following syscalls:
  socket(PF_INET6, SOCK_RAW, IPPROTO_RAW) = 3
  sendto(3, NULL, 0, 0, {sa_family=AF_INET6, sin6_port=htons(0), inet_pton(AF_INET6, "ff00::", &sin6_addr), sin6_flowinfo=0, sin6_scope_id=0}, 28) = -1 EPERM

A similar report is triggered in net/ipv4/raw.c if we use a PF_INET socket
instead of a PF_INET6 one.

Signed-off-by: Alexander Potapenko 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

net: ipv6: Do not duplicate DAD on link up

2017-05-14T12:06:01+00:00

[ Upstream commit 6d717134a1a6e1b34a7d0d70e953037bc2642046 ]

Andrey reported a warning triggered by the rcu code:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 5911 at lib/debugobjects.c:289
debug_print_object+0x175/0x210
ODEBUG: activate active (active state 1) object type: rcu_head hint:
        (null)
Modules linked in:
CPU: 1 PID: 5911 Comm: a.out Not tainted 4.11.0-rc8+ #271
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS Bochs 01/01/2011
Call Trace:
 __dump_stack lib/dump_stack.c:16
 dump_stack+0x192/0x22d lib/dump_stack.c:52
 __warn+0x19f/0x1e0 kernel/panic.c:549
 warn_slowpath_fmt+0xe0/0x120 kernel/panic.c:564
 debug_print_object+0x175/0x210 lib/debugobjects.c:286
 debug_object_activate+0x574/0x7e0 lib/debugobjects.c:442
 debug_rcu_head_queue kernel/rcu/rcu.h:75
 __call_rcu.constprop.76+0xff/0x9c0 kernel/rcu/tree.c:3229
 call_rcu_sched+0x12/0x20 kernel/rcu/tree.c:3288
 rt6_rcu_free net/ipv6/ip6_fib.c:158
 rt6_release+0x1ea/0x290 net/ipv6/ip6_fib.c:188
 fib6_del_route net/ipv6/ip6_fib.c:1461
 fib6_del+0xa42/0xdc0 net/ipv6/ip6_fib.c:1500
 __ip6_del_rt+0x100/0x160 net/ipv6/route.c:2174
 ip6_del_rt+0x140/0x1b0 net/ipv6/route.c:2187
 __ipv6_ifa_notify+0x269/0x780 net/ipv6/addrconf.c:5520
 addrconf_ifdown+0xe60/0x1a20 net/ipv6/addrconf.c:3672
...

Andrey's reproducer program runs in a very tight loop, calling
'unshare -n' and then spawning 2 sets of 14 threads running random ioctl
calls. The relevant networking sequence:

1. New network namespace created via unshare -n
- ip6tnl0 device is created in down state

2. address added to ip6tnl0
- equivalent to ip -6 addr add dev ip6tnl0 fd00::bb/1
- DAD is started on the address and when it completes the host
  route is inserted into the FIB

3. ip6tnl0 is brought up
- the new fixup_permanent_addr function restarts DAD on the address

4. exit namespace
- teardown / cleanup sequence starts
- once in a blue moon, lo teardown appears to happen BEFORE teardown
  of ip6tunl0
  + down on 'lo' removes the host route from the FIB since the dst->dev
    for the route is loobback
  + host route added to rcu callback list
    * rcu callback has not run yet, so rt is NOT on the gc list so it has
      NOT been marked obsolete

5. in parallel to 4. worker_thread runs addrconf_dad_completed
- DAD on the address on ip6tnl0 completes
- calls ipv6_ifa_notify which inserts the host route

All of that happens very quickly. The result is that a host route that
has been deleted from the IPv6 FIB and added to the RCU list is re-inserted
into the FIB.

The exit namespace eventually gets to cleaning up ip6tnl0 which removes the
host route from the FIB again, calls the rcu function for cleanup -- and
triggers the double rcu trace.

The root cause is duplicate DAD on the address -- steps 2 and 3. Arguably,
DAD should not be started in step 2. The interface is in the down state,
so it can not really send out requests for the address which makes starting
DAD pointless.

Since the second DAD was introduced by a recent change, seems appropriate
to use it for the Fixes tag and have the fixup function only start DAD for
addresses in the PREDAD state which occurs in addrconf_ifdown if the
address is retained.

Big thanks to Andrey for isolating a reliable reproducer for this problem.
Fixes: f1705ec197e7 ("net: ipv6: Make address flushing on ifdown optional")
Reported-by: Andrey Konovalov 
Signed-off-by: David Ahern 
Tested-by: Andrey Konovalov 
Signed-off-by: David S. Miller 
Signed-off-by: Greg Kroah-Hartman

ipv6: check raw payload size correctly in ioctl

2017-04-26T18:59:35+00:00

In situations where an skb is paged, the transport header pointer and
tail pointer can be the same because the skb contents are in frags.

This results in ioctl(SIOCINQ/FIONREAD) incorrectly returning a
length of 0 when the length to receive is actually greater than zero.

skb->len is already correctly set in ip6_input_finish() with
pskb_pull(), so use skb->len as it always returns the correct result
for both linear and paged data.

Signed-off-by: Jamie Bainbridge 
Signed-off-by: David S. Miller

ipv6: check skb->protocol before lookup for nexthop

2017-04-26T18:51:26+00:00

Andrey reported a out-of-bound access in ip6_tnl_xmit(), this
is because we use an ipv4 dst in ip6_tnl_xmit() and cast an IPv4
neigh key as an IPv6 address:

        neigh = dst_neigh_lookup(skb_dst(skb),
                                 &ipv6_hdr(skb)->daddr);
        if (!neigh)
                goto tx_err_link_failure;

        addr6 = (struct in6_addr *)&neigh->primary_key; // <=== HERE
        addr_type = ipv6_addr_type(addr6);

        if (addr_type == IPV6_ADDR_ANY)
                addr6 = &ipv6_hdr(skb)->daddr;

        memcpy(&fl6->daddr, addr6, sizeof(fl6->daddr));

Also the network header of the skb at this point should be still IPv4
for 4in6 tunnels, we shold not just use it as IPv6 header.

This patch fixes it by checking if skb->protocol is ETH_P_IPV6: if it
is, we are safe to do the nexthop lookup using skb_dst() and
ipv6_hdr(skb)->daddr; if not (aka IPv4), we have no clue about which
dest address we can pick here, we have to rely on callers to fill it
from tunnel config, so just fall to ip6_route_output() to make the
decision.

Fixes: ea3dc9601bda ("ip6_tunnel: Add support for wildcard tunnel endpoints.")
Reported-by: Andrey Konovalov 
Tested-by: Andrey Konovalov 
Cc: Steffen Klassert 
Signed-off-by: Cong Wang 
Signed-off-by: David S. Miller

net: ipv6: regenerate host route if moved to gc list

2017-04-25T18:04:44+00:00

Taking down the loopback device wreaks havoc on IPv6 routing. By
extension, taking down a VRF device wreaks havoc on its table.

Dmitry and Andrey both reported heap out-of-bounds reports in the IPv6
FIB code while running syzkaller fuzzer. The root cause is a dead dst
that is on the garbage list gets reinserted into the IPv6 FIB. While on
the gc (or perhaps when it gets added to the gc list) the dst->next is
set to an IPv4 dst. A subsequent walk of the ipv6 tables causes the
out-of-bounds access.

Andrey's reproducer was the key to getting to the bottom of this.

With IPv6, host routes for an address have the dst->dev set to the
loopback device. When the 'lo' device is taken down, rt6_ifdown initiates
a walk of the fib evicting routes with the 'lo' device which means all
host routes are removed. That process moves the dst which is attached to
an inet6_ifaddr to the gc list and marks it as dead.

The recent change to keep global IPv6 addresses added a new function,
fixup_permanent_addr, that is called on admin up. That function restarts
dad for an inet6_ifaddr and when it completes the host route attached
to it is inserted into the fib. Since the route was marked dead and
moved to the gc list, re-inserting the route causes the reported
out-of-bounds accesses. If the device with the address is taken down
or the address is removed, the WARN_ON in fib6_del is triggered.

All of those faults are fixed by regenerating the host route if the
existing one has been moved to the gc list, something that can be
determined by checking if the rt6i_ref counter is 0.

Fixes: f1705ec197e7 ("net: ipv6: Make address flushing on ifdown optional")
Reported-by: Dmitry Vyukov 
Reported-by: Andrey Konovalov 
Signed-off-by: David Ahern 
Acked-by: Martin KaFai Lau 
Acked-by: Eric Dumazet 
Signed-off-by: David S. Miller

ipv6: fix source routing

2017-04-25T17:59:24+00:00

Commit a149e7c7ce81 ("ipv6: sr: add support for SRH injection through
setsockopt") introduced handling of IPV6_SRCRT_TYPE_4, but at the same
time restricted it to only IPV6_SRCRT_TYPE_0 and
IPV6_SRCRT_TYPE_4. Previously, ipv6_push_exthdr() and fl6_update_dst()
would also handle other values (ie STRICT and TYPE_2).

Restore previous source routing behavior, by handling IPV6_SRCRT_STRICT
and IPV6_SRCRT_TYPE_2 the same way as IPV6_SRCRT_TYPE_0 in
ipv6_push_exthdr() and fl6_update_dst().

Fixes: a149e7c7ce81 ("ipv6: sr: add support for SRH injection through setsockopt")
Signed-off-by: Sabrina Dubroca 
Reviewed-by: Hannes Frederic Sowa 
Signed-off-by: David S. Miller

ipv6: move stub initialization after ipv6 setup completion

2017-04-25T15:43:16+00:00

The ipv6 stub pointer is currently initialized before the ipv6
routing subsystem: a 3rd party can access and use such stub
before the routing data is ready.
Moreover, such pointer is not cleared in case of initialization
error, possibly leading to dangling pointers usage.

This change addresses the above moving the stub initialization
at the end of ipv6 init code.

Fixes: 5f81bd2e5d80 ("ipv6: export a stub for IPv6 symbols used by vxlan")
Signed-off-by: Paolo Abeni 
Acked-by: Cong Wang 
Signed-off-by: David S. Miller